CHARACTERIZATION OF Fusarium oxysporum f. sp. vasinfectum [(Atk.) Snyder & Hansen] CAUSING WILT OF COTTON AND ITS MANAGEMENT
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Date
2018-06
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JAU,JUNAGADH
Abstract
Cotton (Gossypium spp.) is an important fiber cash crop, which was found to be suffering from Fusarium wilt disease in moderate form in Saurashtra region of Gujarat state.
Cotton plant showing typical wilt symptoms in pot and field conditions. Leaves turned yellow and lose its turgidity. Collar region of plant was dry and turned to brown. When roots of such infected plants were spilt vertically from collar region to downwards, the vascular system showed brownish discoloration. The repeated isolation from infected plants revealed the association of Fusarium oxysporum f. sp. vasinfectum. On the basis of morphological, cultural, molecular characters and pathogenicity test it identified as Fusarium oxysporum f. sp. vasinfectum. The pathogenicity was successfully proved by soil inoculation method.
Biochemical study revealed that total phenol and peroxidase enzyme were higher in disease infected plant parts (leaf and root) comparison to healthy plant parts.
In laboratory screening of different agro-chemicals, tebuconazole 25.9 EC was found to be quite effective in inhibiting the radial growth of test pathogen among systemic group of fungicides, while in non-systemic group of fungicides, copper oxychloride 50 WP and in case of fungicide combinations tebuconazole 50 +
Abstract
trifloxystrobin 25 WP were significantly inhibited the growth of test fungus under in vitro.
Among the fungal and bacterial antagonists, T. harzianum was most effective in growth inhibition of test fungus. Next best was T. viride followed by B. subtilis, T. koningii, T. atroviride and P. fluorescences.
Among nine phytoextracts of indigenous plants were evaluated in vitro against test pathogen using poisoned food technique, maximum inhibition was recorded in garlic cloves extract (72.15%), followed by neem leaves extract (65.34%).
Effective antagonists and fungicides were tested in net house condition in pot culture. Among two antagonists and six fungicides tested, the combination of carboxin 37.5 + thiram 37.5 WP showed minimum plant disease incidence (PDI) followed by carbendazim 50 WP.
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PLANT PATHOLOGY